Key Points:

Two of New Zealand's most powerful tribes - with combined assets valued at $1.2 billion - have signed a deal which signals their intent to work together.

On Friday Ngai Tahu and Tainui signed a memorandum of understanding which forms the basis for a working commercial relationship.

At the signing at Arowhenua Marae in South Canterbury little detail was on display. The ceremony was largely a symbolic display of commitment for members of both iwi.

Both tribes are well established as regional players in their own backyards.

Tainui Group Holdings is the biggest property developer in Waikato. It has been a good year for the group, which is set to open a new hotel in December, and after five years of growth it announced it owned assets worth $551 million earlier in the year.

Meanwhile, Ngai Tahu announced in October an $80.3 million net surplus, up from last year's $9.3 million result. The southern tribe also announced recently a deal which will see it develop whale watching opportunities with SeaWorld on Australia's Gold Coast.

But now the push is on to work together in joint ventures and other commercial projects.

Tainui Group Holdings chief executive Mike Pohio said the commercial arms would flesh out the details of how the relationship would work, but there was a degree of caution.

"We're all very enthusiastic about it happening but the important thing is making sure that it works. In that regard we want to put in place the right structures at the right time."

In the meantime the two groups would look at opportunities asthey arose, said Mr Pohio.

Ngai Tahu kaiwhakahaere (chairman) Mark Solomon said sharing information between iwi was good for business and both tribes needed to lead.

"I've always been a staunch supporter of that. Collectively, we've got all the networks we need - we need to be building our economies together."

Labour MP Shane Jones, who helped to triple the value of Maori fisheries assets secured in the 1992 Sealord deal to $750 million, said it made sense that the two should work together. "One simply needs to look at the bigger companies when they work together - they can seize more opportunities."

In the long term, iwi businesses interests were tied up with Kiwi interests, he said.

"You need to remember that Maori trusts and iwi organisations, they're very rarely sellers. They like to hold assets for a long, long time, and given the amount of foreign ownership in the economy, it's good that tribes work together and help to buy back some of those assets that looked lost."